Carbohydrates are a type of acquirement found in many foods and beverages. Most carbohydrates are naturally occurring in plant-based foods, such as grains. Food manufacturers also add carbohydrates to processed foods in the form of starch or added sugar. As with all our approaches to food ingredients/constituents we will first examine the structure of carbohydrates and then try to elucidate how their structures allow them to function as they do. As their name suggests, carbohydrates basically made up from sugar and water, i. E.
Xx(H2O)y, although this ratio is often not strictly true and occasionally other atoms may be present. The carbons are arranges in a chain (most often 5-6 atoms) functionalities with alcohol groups. The terminal carbon either carries either an alder or a ketene functional group. Carbohydrates are classified based on size of base carbon chain, number of sugar units, location of C=O and psychotherapy. Classifications of carbohydrate are incarcerations, disaccharide, electrocardiographs, and polysaccharides. Macroeconomics is the smallest possible sugar unit.
Examples include glucose, calaboose or fructose. When we talk about blood sugar we are referring to glucose in the blood; glucose is a major source of energy or a cell. In human nutrition, calaboose can be found most readily in milk and dairy products, while fructose is found mostly in vegetables and fruit. When incarcerations merge together in linked groups they are known as polysaccharides. Disaccharide is two macroeconomics molecules bonded together. Polysaccharides are polymers. A simple compound is a monomer, while a complex compound is a polymer which is made of two or more monomers.
Disaccharide are polysaccharides – “poly… ” Specifies any number higher than one, while specifies exactly two. Examples of disaccharide include lactose, maltose, and sucrose. If you bond one glucose molecule with a fructose molecule you get a sucrose molecule. Sucrose is found in table sugar, and is often formed as a result of photosynthesis (sunlight absorbed by chlorophyll reacting with other compounds in plants). If you bond one glucose molecule with a calaboose molecule you get lactose, which is commonly found in milk.
Starch, glycogen, Textron and cellulose are polysaccharides. Polysaccharides differ not only in the natural of their component incarcerations but also in the length of their chains and in the amount of chain branching that occurs. Polysaccharides function as storage trials, structural components, or protective substances. Thus, starch ( which exists in two forms: amylase and implementation ), glycogen and other storage polysaccharides, as readily metabolize food, provide energy reserves for cells.
Chitin and cellulose provide strong support for the skeletons of arthropods and green plants, respectively. In this experiment those activity that had been carried out means to determine the carbohydrate class of an unknown by carrying out a series of chemical reactions with the unknown and known compounds in each class of carbohydrate such as the Mollies test (general CHOC), Beebread’s test incarcerations), Feeling’s test (reducing sugars), Benedicts test (reducing sugars) and Iodine test (amylase). ACTIVITY 3. , MOLLIES TEST: A GENERAL TEST FOR CARBOHYDRATES OBJECTIVE: To test the carbohydrate solution MATERIALS: 1 % of carbohydrate solutions( lactose, glucose, starch, sucrose, cellulose, fructose, apple and cabbage ), distilled water(as control tube), concentrated sulfuric acid, Mollies reagent. APPARATUS: Test tubes, test tube holder, dropper, ml pipette, glass rod, test tube rack, fume cupboard CAUTION: Mulish reagent contains concentrated sulfuric acid , which is toxic and corrosive. It can cause severe burns. Prevent eye, skin clothing, and combustible material contact.
Avoid ingesting the substance. Elf you spill any reagent or acid, immediately notify your laboratory instructor. NOTE: Do not place your thumb over the open end off test tube when mixing its contents. Your laboratory instructor will suggest ways in which you can safely and thoroughly mix the contents of a test tube. PROCEDURES: 1. 2 ml of each of the 1% carbohydrate solutions that have been prepared is added into one set of labeled test tubes. 2. 2 drops of Mollies reagent are added to each test tube and is mixed well with a clean glass stirring rod. . The test tube is inclined.
Then ml of concentrated sulfuric acid is added slowly and carefully down the side of the tube to form a layer below the sugar solution. ( This step is performed inside the fume cupboard ). 4. The resulting solution did not been shook or mixed. 5. The change of the solution is observed and recorded. (A purple ring at the interface is indicative of a carbohydrate ). 6. The test solutions containing Mollies reagent is discarded into the container provided by laboratory instructor. RESULT: DISCUSSION: Carbohydrates undergo dehydration reactions (loss of water) in the presence f concentrated sulfuric acid.
Pentose and hoses form five member oxygen containing rings on dehydration. The five member ring, known as formula, further reacts with Mollies reagent to form colored compounds. Pentose are then dehydrated to formula, while hoses are dehydrated to 5- hydroxymethylfurfural. Either of these leaderless, if present, will condense with two molecules of naphtha to form a purple-colored product. A positive reaction is indicated by appearance of a purple ring at the interface between the acid and test layers. Incarcerations give a rapid positive test. Glucose and fructose are macroeconomics.
Disaccharide and polysaccharides react more slowly than macroeconomics. Sucrose and lactose are disaccharide which also gave purple color ring. Starch and cellulose gave slightly purple color because they are polysaccharides. Distilled water gave negative test because it is not carbohydrate. A large apple has around 28-31 grams of carbohydrate. Apple and cabbage contain carbohydrate so that they gave purple ring in this test. CONCLUSION: Glucose, lactose, fructose, sucrose, starch and cellulose all are carbohydrates which give positive test for Mollies test.
A sample of distilled water is prepared and tested as the controlling sample. ACTIVITY 3. 2, BEEBREAD’S TEST:A GENERAL TEST TO DISTINGUISH BETWEEN MACROECONOMICS AND DISACCHARIDE To distinguish the given carbohydrate solutions as incarcerations or disaccharide. MATERIALS: fructose), distilled water (as control tube), Beebread’s reagent APPARATUS: Test tubes, test tube holder, 5 ml pipette, pipette filler, stop watch, water bath CAUTION : Beebread’s reagent is corrosive and an irritant. If you spill any of the solution on yourself or on the bench, immediately notify your laboratory instructor.
PROCEDURES 1 . 5 ml of each of the carbohydrate solutions is added into one set of the labeled test tubes. . 5 ml of Beebread’s reagent is added to each test tubes. 3. The contents of each tube are shook well. All the tubes are placed in an actively boiling water bath at the same time. 4. After the water starts boiling again, the solutions is heated for 3. 5 min. ( Timing is important since a false positive test can be obtained for incarcerations with disaccharide, if the disaccharide are heated for more than 3. 5 min thereby breaking down ( hydroplaning ) to incarcerations ). 5.
During this period, the tubes are observed closely and any change of clarity of the solutions is noted. ( A positive test for incarcerations s the appearance of a red precipitate of CLICK within 1 or 2 minutes, if no precipitate forms it indicates the presence of a disaccharide). RESULT: 1% CARBOHYDRATE SOLUTION FORMATION OF RED PRECIPITATE Fructose Yes Glucose Cellulose No Lactose Sucrose Starch Distilled water(as control tube) Beebread’s test distinguishes incarcerations from disaccharide. Positive test for incarcerations is the appearance of red precipitate (Such) within 1-2 minutes.
If no precipitate formed, indicates the presence of disaccharide. The red precipitate come from the reaction between the reduction of copper (II) acetate o copper(l) oxide (Such). RICH + cue+ + 21-420 RICOH + Couch + UH+ The alder group of the macroeconomics which normally forms a cyclic hemispherical is oxidized to the carboxylic. Glucose and fructose which are incarcerations show positive result in this test. Reducing disaccharide undergo the same reaction, but do so at a slower rate. So, the timing to heat the sample is set to 3. 5 minutes. However, the samples are heated no more than 3. Minutes to prevent the disaccharide breaking down to macroeconomics. Lactose, sucrose, cellulose, starch and distilled water showed negative result in this test. Only macroeconomics will give an immediate red precipitate in Beebread’s test that is glucose and fructose the other remaining solutions which are cellulose, lactose, sucrose, starch and distilled water do not show any changes. ACTIVITY 3. 3 FEELING TEST: FOR REDUCING SUGARS To distinguish the reducing sugars and non-reducing sugars 1% of carbohydrate solutions ( glucose, fructose, cellulose, lactose, sucrose, starch ), distilled water(as control tube), Feeling solution A ( 69. 8 grams copper (II) sulfate penetrated dissolved in 1 liter of distilled water), Feeling solution B ( 346 grams Rockwell salt ( potassium sodium treated dehydrated) and 120 grams sodium hydroxide in 1 liter of distilled water) APPARATUS: 5 ml pipette, test tubes, test tube holder, test tube rack, pipette filler, stop watch PROCEDURES: 1. 5 ml of carbohydrate solutions is added into one set of test tubes. 2. By using different glass pipettes, 5 ml of Feeling A and 5 ml of Feeling B are added into each test tubes. 3. The solution is heated in a boiling water bath for 5-10 minutes. 4.
Red brick precipitate is formed for positive results. 5. Changes in test tubes are recorded. Samples Result Positive-red brick precipitate Negative-no changes Distilled water Feeling’s solution is used to test for the presence of a reducing sugar. Feeling’s solution was based on the alder or ketene groups in the sugar structures. A sugar is classified as a reducing sugar only if it has an open-chain form with an alder group or a free hemispherical group. The presence of leaderless but not stones is detected by reduction of the deep blue solution of copper(al) to a red precipitate of insoluble copper oxide.
Fructose, glucose and lactose show positive result in this test. All incarcerations are reducing sugars. Many disaccharide, like lactose, also have a reducing form, as one of the two units may have an open-chain form with an alder group. However, sucrose, in which the anorexic carbons of the two units are linked together, are non-reducing disaccharide since neither of the rings is capable of opening. Polysaccharides (sugars with multiple chemical rings) are non-reducing sugars. Polysaccharides have closed structures, which use free atoms to bond together their multiple rings, and take a much longer time to be broken down.
So, starch and cellulose which are polysaccharides have negative result in Feeling’s test. Distilled water is not reducing sugar also shows negative result. Feeling test is the common test which is used to determine the presence of reducing sugar. Fructose, lactose and glucose are reducing sugars which give brick red precipitate after the solutions are heated. ACTIVITY 3. 4 BENEDICTS TEST: FOR REDUCING SUGARS To test for reducing sugars starch ), MM hydrochloric acid (HCI), Benedicts reagent, distilled water APPARATUS: Test tubes, test tube holder, test tube rack, 5 ml pipette, pipette filler, dropper, stop watch, water bath PROCEDURES 1. Ml of Benedicts reagent and 2 ml of carbohydrate are added to a test tube ND each tube is shook thoroughly. 2. All the tubes are placed in a boiling water bath at the same time. The solutions are heated for 5-6 min. 3. Any changes in color, in the transparencies and in the formation and color of any precipitate are observed and recorded. 4. Later, 4 drops of MM HCI are added to 5 ml of 1 % sucrose solution and is heated in the boiling water bath for 5 min. 5. 1 % starch solution is treated in the same way but the heating period was extended to 25-30 min. 6. -2 ml of each of solution is applied with Benedicts test in the same manner as before. 7. The results are compared with those obtained without acid treatment. Sugar solution Result of color of the solution Light blue Brick red precipitate are formed Light blue + white precipitate Sucrose + HCI Starch + HCI Light green The Benedicts test is used to detect the presence of reducing sugars (sugars with a free alder or ketene group) such as glucose, fructose and lactose. All incarcerations are reducing sugars; they all have a free reactive carbonyl group. Some disaccharide have exposed carbonyl groups and are also reducing sugars.
Lactose which is disaccharide also called reducing sugar as it has the exposed carbonyl groups. Other disaccharide such as sucrose and starch are non-reducing sugars and will not react with Benedicts solution. Benedicts reagent is a mild oxidant with Cuscus, Cue (II) sulfate, as one of the reagents. In the presence of a reducing sugar, the blue solution of Cue (II) or Cue+2, is changed to a brick red/brown precipitate of Copper (l) or Cue+l oxide,Such. If there a small or large amount of the reducing sugar present, the color would range from green to brick red respectively.
RICH + cue+ + UH- RICOH + Sucrose indirectly produces a positive result with Benedicts such + UH agent if heated with dilute hydrochloric acid prior to the test, although after this treatment it is no longer sucrose. The addition of HCI hydrolysis the non- reducing sugar, as it split it up into its component monomers. The monomers are reducing sugars which gave the positive result on the second reducing sugar test. The acidic conditions and heat break the glycoside bond in sucrose through hydrolysis. The products of sucrose decomposition are glucose and fructose, both of which can be detected by Benedicts reagent, as described above.